December in Rockford averages a daily high of 1.7°C with nights around -6.6°C. Expect roughly 9.7 wet days totalling 50.4mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Rockford is August–September.
Based on ROCKFORD GREATER ROCKFORD AIRPORT, IL US (8.7km), 1995–2024. 30 years of December data.